Sub-cooling steam condensate in tube side of heat exchanger for an absorption refrigeration system



A g- 6, 1966 R. c. VAN MEERBEKE 3, 6, 68

SUB-COOLING STEAM CONDENSATE IN TUBE SIDE OF HEAT EXCHANGER FOR AN ABSORPTION REFRIGERATION SYSTEM Filed Jan. 19, 1965 2 Sheets-Sheet 1 RONALD c. VAN MEER-BEKE %awll N- 1966 R. c. VAN MEERBEKE 3,266,268

SUB COOLING STEAM CONDENSATE IN TUBE SIDE OF HEAT EXCHANGER FOR AN ABSORPTION REFRIGERATION SYSTEM Filed Jan. 19. 1965 2 Sheets-Sheet 2 I28 I 6 I32 RONALD C. VAN MEERBEKE United States Patent 3,266,268 SUB-COOLING STEAM CONDENSATE IN TUBE SIDE OF HEAT EXCHANGER FOR AN ABSORP- TION REFRIGERATION SYSTEM Ronald C. Van Meerbeke, Keyport, N..I., assignor to Worthington Corporation, Harrison, NJ, a corporation of Delaware Filed Jan. 19, 1965, Ser. No. 426,637 4 Claims. (Cl. 62--489) This invention relates generally to an absorption refrigeration system. More particularly this invention relates to an improved arrangement for sub-cooling the steam condensate from the generator by passing it in indirect heat exchange relationship with the weak solution in the tube side headers of the heat exchanger disposed between the generator and the absorber of said system.

In accordance with the present invention an absorption refrigeration system is provided with a heat exchange means which comprises a tube and shell casing disposed intermediate the absorber and the generator. Strong solution from the generator passes in indirect heat exchange relation in the shell side with weak solution from the absorber. The Weak solution passes through the tube side in which a steam condensate tube bundle is disposed to pass condensate in indirect heat exchange relation with the weak solution.

Heretofore, some absorption refrigeration systems required individual heat exchangers, one of which was utilized to sub-cool steam condensate and the other of which was used to pre-heat the Weak solution by passing it in indirect heat exchange relationship with the strong solution. However, this practice is costly, uneconomical and requires a system of larger size and greater bulk.

An object of the present invention is to provide an improved arrangement for sub-cooling the steam condensate which overcomes the prior art difficulties; which provides for sub-cooling of the steam condensate by passing it through the tube side headers to sub-cool the condensate and add sensible heat to the brine solution in said headers; which allows the condensate to be cooled, thus avoiding flashing thereof on discharge from the system; which improves total heat transfer from the steam and steam condensate to the brine solution in the system to decrease the required quantity of steam so that a substantial saving of steam is realized; which acts to preheat the weak solution in the tube side by the steam condensate which passes in parallel relationship to the strong solution flowing in the shell side of theheat exchanger.

Another object of this invention is to provide an improved arrangement for sub-cooling the steam condensate which is reliable, economical and utilizes the minimum of space; which utilizes the sensible heat of the condensate to pre-heat the brine solution therewith; which avoids the use of steam traps which would otherwise be required.

Other objects and advantages Will be apparent from the following description of one embodiment of the invention and the novel features will be particularly pointed out hereafter in the claims; reference being had to the accompanying drawings forming a part of this specification wherein like reference characters designate corresponding parts in the several views. Furthermore, the phraseo-logy of terminology employed herein is for purpose of description and not of limitation.

In the drawings:

FIGURE 1 is a diagrammatic illustration of an absorption refrigeration system embodying the invention.

FIGURE 2 is a sectional view taken along line 2-2 of FIGURE 3.

FIGURE 3 is a sectional view taken along the line 3-3 .of FIGURE 2.

An absorption refrigeration system, per se, is Well known in the art. Such system will include an absorber, an evaporator, a generator, a condenser, and a heat exchanger operatively disposed between the absorber and the generator. A brine or saline solution is circulated through the absorption refrigeration system in varying concentrations. The brine solution is made up of a suitable mixture of an absorbent, such as lithium bromide, and a refrigerant, such as Water. The brine solution in the system is referred to as a weak solution: whenever it contains such a quantity of refrigerant so as to render the solution weak in absorbing properties. A weak solution will generally consist of between 55% to 62% lithium bromide. The brine solution in the system is referred to as a strong solution whenever the quantity or refrigerant contained in such solution is deficient of refrigerant so as to enhance the refrigerant absorption properties of said solution. A strong solution will generally consist of between 66% through 69% lithium bromide.

One type of general absorption refrigeration system is disclosed in Patent No. 3,154,930, issued November 3, 1964, entitled Refrigeration Apparatus. The particular multipath cross flow heat exchanger is disclosed in a pending application of David Aronson, Serial No. 415,121, filed December 1, 1964, entitled, Heat Exchange Means for an Absorption Refrigeration System. These applications may be referred to for a more detailed description of the operation and components of the absorption refrigeration system, as the present application will only describe such system and heat exchanger therefore in sufficient detail to give a clear understanding of the present invention. Of course the present invention is readily adaptable for use in any heat exchanger which has a shell side and a tube side.

In the embodiment of the invention shown in the drawings, the improved arrangement for sub-cooling the steam condensate is designated generally as 20, and is illusrated diagrammatically within heat exchanger 22 which is incorporated into absorption refrigeration system 24.

Absorption refrigeration system 24, as shown in FIG- URE 1, includes an absorber 26 and an evaporator 28 formed in a low pressure longitudinally, extending shell 36. A high pressure longitudinally extending shell 32 is disposed below shell and has disposed therein a condenser 34, a generator 36, and heat exchanger 22.

Shell 30 has a partition 38 extending therethrough to separate the absorber 26 from evaporator 28. One end of partition 38 has an upturned edge 40 which defines a passage 42 between edge 40 and the wall of shell 30 and also serves as a spray guard. The other end of partition 38 has a sump 44 formed therein whereby partition 38 will serve as a liquid holding means in which the weak solution in absorber 26 may be collected. A line 46 is connected to deliver weak solution from the upper level of sump 44 through heat exchanger 22, wherein it will pass in indirect heat exchange relationship with strong solution leaving generator 36 prior to the weak solution entering the generator 36. Since the pressure of the generator 36 is substantially higher than the pressure in absorber 26, a sufficient head is established in line 46 to permit the flow in the direction indicated by the arrow. The pre-heated weak solution will enter the generator as shown in FIGURES l and 2 through opening 48 of wall 50 which separates the generator 36 and heat exchanger Generator 36 includes a liquid holding enclosure maintained at a pressure of about 3.0 inches of mercury. The line 52 extends into generator 36 and connects to a tube bundle 54 for the delivery of steam from a suitable source (not shown). Heat is thus supplied to the generator wherein the weak solution which entered through opening 48 passes in indirect heat exchange relationship with tube bundle 54 and will be boiled to as to drive oif the refrigerant vapor, which passes upwardly towards condenser 34. After being concentrated to a strong solution it will pass out of the generator 36 over or around duct wall 55 and through opening 56 wherein it will enter heat exchanger 22 to pre-heat the incoming weak solution. The somewhat cooled strong solution will pass from heat exchangers through line 58 and be introduced into a flow mixer 60 in which weak solution is also delivered from sump 44 through line 62.

In flow mixer 60 the strong solution from line 58 and the weak solution from line 62 will combine to form a mixture of intermediate strength, which mixture will be drawn in line 64'by the suction of absorber pump 66. Pump 66 will discharge the intermediate solution into line 68 for delivery to spray header 70, located in absorber 26. Spray header 70 has a plurality of nozzles 72 through which the intermediate solution is sprayed on to the surface of absorber tube bundle 74 so as to effect a continuous condensation to maintain the absorber interior at an atmosphere of 0.3 inch of mercury.

vaporized refrigerant enters absorber 26 through passage 42 wherein it will be absorbed into the sprayed solution through the absorption process on contact with said solution. Tube bundle 74 serves to cool the solution and remove the heat liberated to the solution when the refrigerant vapor is absorbed. Sufficient refrigerant vapor is absorbed by the sprayed solution so as to collect in sump 44 in the form of weak solution.

Cooling water enters line 76 from a suitable source (not shown) for distribution through absorber tube bundle 74 and is discharged through line 78 where it will pass to condenser tube bundle 80, in which it will condense refrigerant vapor prior to being discharged through line 82 from which it may pass to a cooling tower (not shown) for cooling and subsequent recirculation. The quantity of cooling water flowing in tube bundles 74 and may be selectively regulated automatically by valve 84 which is controlled responsive to the discharge temperature from condenser 34 in a well known manner, as by bulb 86 and capillary 88.

Condenser 34 is formed in shell 32 by transverse partition 90 which has one end connected to shell 32 and the other end 92 extending upwardly therefrom to form a passage 94 through which the refrigerant vapor from generator 36 will enter condenser 34. The refrigerant vapor will come in contact with condenser tube bundle 80 and be cooled and condensed thereby. The refrigerant condensate will accumulate at the bottom of the condenser and (be forced by the existing pressure differential to pass through line loop 96 to evaporator 28, wherein a portion of the condensate will flash and the remainder of the condensate will collect in the bottom thereof.

The refrigerant condensate entering evaporator 28 from line loop 96 will collect at the bottom portion thereof and will be drawn off in line 104 to the suction of refrigeration pump 106, which will deliver refrigerant in line 108 for discharge through spray header 100. The refrigerant is sprayed from nozzles 98 of spray header 100 over evaporator tube bundle 102 through which water passes to be chilled. The refrigerant will evaporate on the surface of the tube bundle 102, thereby taking heat from the water circulating in the tube bundle 102 and chilling it. The refrigerant vapor in evaporator 28 passes through passage 42 into absorber 26.

Suitable purge means (not shown) may be utilized in the systemto remove non-condensibles from the revnt'such flashing, as the steam condensate is formed in the tube bundle 54 it will be delivered through line to the steam condensate tube bundle 112 disposed in the therefrom is negligible.

bottom of heat exchanger 22 in the tube side 22a thereof, as shown in FIGURES 1, 2 and 3, wherein the condensate will be circulated and sub-cooled prior to being discharged in line 114, as more fully described hereinafter. Regulator valve 116 is disposed in line 114 in order to control the rate of discharge of steam condensate from the system.

Heat exchanger 22 as shown in FIGURE 1 is formed in an integral structure with generator 32 and is formed on the underside of wall 50 of elongated shell 32. Heat exchanger 22 is of the shell and tube. type in which the tube side is defined generally as 22a and the shell side is defined generally as 22b.

Longitudinally extending vertical partitions 120 and 122 are illustrated in FIGURES 2 and 3, extend in spaced relationship to each other substantially the length of heat exchanger 22 to form a flow passage 124 therebetween. Opening 56, flow passage 124 and the discharge line 58 define the shell side of heat exchanger 22.

A plurality of transverse partitions 126 extend between partitions 120 and 122, respectively, and the wall of shell 32 to form a first header 128, a last header 130 and a plurality of intermediate headers 132. A plurality of transverse tube tbundles extend from headers 128, 130 and 132 to form a multipath continuous flow series through flow passage 124. The tube side 22a of heat exchanger 22 is defined by first header 128, last header 130 and intermediate headers 132 which are connected in the multipath continuous flow series by the plurality of tube bundles 134.

The strong solution from generator 36 will enter the shell side 22b through opening 56 and will pass in flow passage 124 in indirect heat exchange relationship with the weak solution crossing said passage in the plurality of tube bundles 134 prior to leaving heat exchanger 22 in line 58.

Conversely, weak solution will pass through the tube side 22a and be preheated in direct heat exchange relationship with the strong solution passing through flow passage 124. The weak solution will enter first header 128 from line 46 and successively pass through tube bundles 134 and intermediate headers 132 so as to cross flow passage 124 repeatedly, prior to entering last header 130 from which the preheated weak solution will leave the heat exchanger 22 through opening 48 and enter generator 36 for purposes more fully described hereinbefore.

The improved arrangement for sub-cooling the steam condensate, as illustrated in FIGURES 2 and 3 includes an inlet header 136 and an outlet header 138 which are connected to shell 32 at opposite ends of the flow passage 124 and have the tube bundles 112 extending therebetween. Accordingly, condensate will enter from line 110 and be distributed by header 136 through tube bundles 112 to outlet header 138 wherein it is collected and discharged through line 114. Tube bundles 112 extend substantially parallel to the flow passage 124. Almost the entire length of tube bundles 112 extend to the headers 128, 130 and 132 of the tube side 22a of heat exchanger 22. Accordingly, the steam condensate flowing in tube bundles 112 will pass in indirect heat exchange relationship to the weak solution in the tube side 22a to thus aid in the preheating of said weak solution and raise the temperature thereof so as to decrease the total heat input required in the generator to boil the \brine solution therein. In this manner the steam condensate will be sub-cooled well below its saturation temperature at atmospheric pressure so that on discharge from line 114 said condensate will not flash.

Even though a small portion of tube bundle 112 passes through the shell side 22b, the heat transfer resulting Of course the design of heat exchanger 22 could readily be modified to provide for tube bundle 112 passing totally within tube side 22a and this is contemplated to be within the scope of the present disclosure.

It will be understood that Various changes in the details, materials, arrangements of parts and operating conditions which have been herein described and illustrated in order to explain the nature of the invention may be made by those skilled in the art within the principles and scope of the invention as expressed in the claims.

What is claimed is:

1. A heat exchange means for a closed cycle absorption refrigeration system in which a brine solution is circulated and which system has an absorber, an evaporator, a generator, a condenser, and conduit means operatively connecting these components to form said system, said heat exchange means comprising:

(a) casing operatively disposed intermediate the ab sorber and the generator,

(b) the casing having a shell side portion and a tube side portion formed therein,

(c) the shell side portion in communication with the strong solution which flows from the generator to the absorber subsequent to passing therethrough;

(d) the tube side portion in communication with the weak solution which flows from the absorber to the generator subsequent to passing in indirect heat exchange relationship with the strong solution in the casing,

(e) a steam condensate tube bundle disposed in the tube side portion of the casing to pass condensate therein in indirect heat exchange relationship with the weak solution whereby steam condensate will be subcooled below the saturation temperature at atmospheric pressure prior to discharge from the casing of the heat exchange means.

2. The combination claimed in claim 1 wherein:

(a) a plurality of headers formed in the tube side portion,

(b) at least one tube bundle extending between the headers of the tube side portion across the shell side portion, and through which the weak solution will pass,

(c) the steam condensate tube bundle disposed in the tube side portion headers.

3. A closed cycle absorption refrigeration system in which a brine solution is circulated therein comprising:

(a) a condenser for receiving and condensing refrigerant,

(b) an evaporator for receiving and evaporating refrigerant,

(c) means communicating the condenser and evaporator in an operative loop,

(d) an absorber for increasing the refrigerant content of the brine solution therein so that it will constitute weak solution, and adapted to receive refrigerant from the evaporator for this purpose,

(e) a generator for decreasing the refrigerant content of the brine solution therein so that it will constitute strong solution, and adapted to pass refrigerant to the condenser,

(f) conduit means communicating the absorber and the generator in an operative loop,

(g) heat exchange means disposed in the conduit means having a shell side portion and a tube side portion to cooperate with each other so that strong solution leaving the generator will pass in indirect heat exchange relationship with weak solution from the absorber,

(h) a steam tube bundle disposed in the generator for heating and boiling the brine solution therein to vaporize a portion of the refrigerant in said solution,

(i) a steam condensate tube bundle in the heat ex change means in communication with the steam tube bundle to pass the steam condensate in indirect heat exchange relationship with the brine solution in the tube side portion of the heat exchange means whereby the condensate will be sub-cooled below its saturation temperature at atmospheric pressure prior to discharge from the heat exchange means.

4. A closed cycle absorption refrigeration system for passing a brine solution in heat exchange relationship therein, such system comprising:

(a) a condenser for receiving and condensing refrii er ant,

(b) an evaporator for receiving and evaporating refrigerant,

(c) conduit means connecting the condenser and evaporator into an operative loop,

((1) an absorber adapted to receive refrigerant from the evaporator, and to increase the refrigerant content of the saline therein, whereby said solution will define a weak solution,

(e) a generator to decrease the refrigerant content of the brine solution therein, and adapted to pass refrigerant to the condenser,

(f) conduit means connected between the absorber and the generator to form an operative loop therebetween,

(g) a heat exchanger disposed in the conduit means communicating the absorber and the generator where in weak solution leaving the absorber will pass in indirect heat exchange relationship with strong solution leaving the generator,

(h) the heat exchanger formed integrally with the generator in a longitudinal casing,

(i) the heat exchanger having a shell side portion for receiving strong solution and a tube side portion for receiving weak solution,

(j) the tube side portion having a plurality of headers formed therein,

(k) the tube side portion having a plurality of tubes forming at least one tube bundle extending across the shell side portion to communicate the tube side portion headers with each other,

(1) steam tube bundle means disposed in the generator,

(m) steam condensate tube bundle means disposed in the headers of the tube side portion of the heat exchanger in communication with the steam tube bundle means in the generator and to receive condensate therefrom to be cooled therein prior to being discharged from the heat exchanger.

References Cited by the Examiner UNITED STATES PATENTS 2,382,255 8/1945 Pyzel 14O 2,482,024 9/ 1949 Ortman et al 16514O X 2,670,933 3/1954 Bay 165140 X 2,819,882 1/1958 Stephani 165-14O 3,154,930 11/1964 Aronson 62489 X FOREIGN PATENTS 281,803 1/1914 Germany. 285,027 4/ 1914 Germany.

LLOYD L. KING, Primary Examiner. 

1. A HEAT EXCHANGE MEANS FOR A CLOSED CYCLE ABSORPTION REFRIGERATION SYSTEM IN WHICH A BRINE SOLUTION IS CIRCULATED AND WHICH SYSTEM HAS AN ABSORBER, AN EVAPORATOR, A GENERATOR, A CONDENSER, AND CONDUIT MEANS OPERATIVELY CONNECTING THESE COMPONENTS TO FORM SAID SYSTEM, SAID HEAT EXCHANGE MEANS COMPRISING: (A) CASING OPERATIVELY DISPOSED INTERMEDIATE THE ABSORBED AND THE GENERATOR, (B) THE CASING HAVING A SHELL SIDE PORTION AND A TUBE SIDE PORTION FORMED THEREIN, (C) THE SHELL SIDE PORTION IN COMMUNICATION WITH THE STRONG SOLUTION WHICH FLOWS FROM THE GENERATOR TO THE ABSORBER SUBSEQUENT TO PASSING THERETHROUGH; (D) THE TUBE SIDE PORTION IN COMMUNICATION WITH THE WEAK SOLUTION WHICH FLOWS FROM THE ABSORBER TO THE GENERATOR SUBSEQUENT TO PASSING IN INDIRECT HEAT EXCHANGE RELATIONSHIP WITH THE STRONG SOLUTION IN THE CASING, (E) A STEAM CONDENSATE TUBE BUNDLE DISPOSED IN THE TUBE SIDE PORTION OF THE CASING TO PASS CONDENSATE THEREIN IN INDIRECT HEAT EXCHANGE RELATIONSHIP WITH THE WEAK SOLUTION WHEREBY STEAM CONDENSATE WILL BE SUBCOOLED BELOW THE SATURATION TEMPERATURE AT ATMOSPHERIC PRESSURE PRIOR TO DISCHARGE FROM THE CASING OF THE HEAT EXCHANGE MEANS. 